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United States Patent |
6,123,726
|
Mori
,   et al.
|
September 26, 2000
|
Portable drive system for artificial heart
Abstract
A portable drive system for an artificial heart can be provided that
includes a blood pump 1 having a blood seal for sealing a rotation shaft
13, a system drive section 45 including a purge solution circulator 20 for
supplying by circulating purge solution to the blood seal 18, a pump
controller 30 for driving the blood pump 1, a power supply means 33 for
supplying electric power thereto, a display 40 for displaying operating
states thereof, a communication interface 50 for transmitting information
to the outside, and a controller means 100 for controlling these
components, a portable transport section 60 for bearing the system drive
section 45, and a connecting section 70 for connecting the blood pump 1
and the system drive section 45. The portable artificial-heart drive
system has high safety and high reliability, is small-sized, lightweight
and easy to use, and can expand the range of life.
Inventors:
|
Mori; Toshio (Chino, JP);
Yamazaki; Kenji (Koganei, JP);
Higuchi; Koji (Okaya, JP);
Kaneko; Keiichi (Suwa, JP)
|
Assignee:
|
Seiko Epson Corporation (Tokyo, JP);
Sun Medical Technology Research Corporation (Suwa, JP)
|
Appl. No.:
|
147996 |
Filed:
|
March 24, 1999 |
PCT Filed:
|
January 26, 1998
|
PCT NO:
|
PCT/JP98/00319
|
371 Date:
|
March 24, 1999
|
102(e) Date:
|
March 24, 1999
|
PCT PUB.NO.:
|
WO99/04834 |
PCT PUB. Date:
|
February 4, 1999 |
Foreign Application Priority Data
Current U.S. Class: |
623/3.27; 600/17; 623/3.13 |
Intern'l Class: |
A61M 001/10 |
Field of Search: |
623/3.1,3.13,3.27,3.15
600/16,17
|
References Cited
U.S. Patent Documents
4704121 | Nov., 1987 | Moise | 623/3.
|
4756302 | Jul., 1988 | Portner et al. | 600/17.
|
5020516 | Jun., 1991 | Biondi et al. | 600/17.
|
5041086 | Aug., 1991 | Koening et al.
| |
5147392 | Sep., 1992 | Inagaki et al. | 623/3.
|
5501216 | Mar., 1996 | Byrd.
| |
5599311 | Feb., 1997 | Raulerson.
| |
5693091 | Dec., 1997 | Larson, Jr. et al.
| |
5755784 | May., 1998 | Jarvik | 623/3.
|
5776110 | Jul., 1998 | Guy et al.
| |
Foreign Patent Documents |
WO 90/15640 | Dec., 1990 | WO.
| |
Primary Examiner: Snow; Bruce
Attorney, Agent or Firm: Watson; Mark P.
Claims
What is claimed is:
1. A portable artificial-heart drive system, comprising:
a blood pump to cause blood to flow, said blood pump comprising:
a motor portion having a drive shaft to drive an artificial heart of a
patient,
a bearing,
a rotation shaft extending from said motor portion and supported by said
bearing,
a pump vane driven via said rotation shaft,
a blood seal for preventing a blood ingredient from entering said bearing,
and
a casing connected to said motor portion and covering said pump vane;
a system drive section comprising:
a purge solution circulator to supply purge fluid solution by circulating
to a contact portion of said blood seal to maintain shaft sealing of said
rotation shaft with respect to blood of the patient,
a motor cable,
a pump controller to electrically control said motor portion in said blood
pump via said motor cable,
a power supply to supply electric power to said pump controller and said
purge solution circulator,
a display to display operating states of at least one of said pump
controller, said power supply and said purge solution circulator and data
thereon,
a communication interface to exchange information with an external device,
and
a controller to control said display, said communication interface, said
pump controller, said power supply and said purge solution circulator;
a movable transport section accommodating said system drive section; and
a connection unit comprising:
a connecting section to connect said blood pump and said system drive
section, and
a skin button section to secure said connecting section on the epidermis of
the patient.
2. A portable artificial-heart; drive system according to claim 1, wherein
said blood seal comprises one of a mechanical seal and an oil seal.
3. A portable artificial-heart drive system according to claim 1, wherein
each of said purge solution circulator, pump controller, display,
controller and communication interface has a respective priority, wherein
said power supply supplies electric power only to at least one of said
purge solution circulator, pump controller, display, controller and
communication interface if the respective priority is high and if a
quantity of electric power remaining in said power supply falls below a
specified value.
4. A portable artificial-heart drive system according to claim 3, wherein
pump controller has the high priority.
5. A portable artificial-heart drive system according to claim 1, wherein
said system drive section comprises at least two pump controllers and
respective power supplies.
6. A portable artificial-heart drive system according to claim 1, further
comprising:
a second pump controller and a second power supply,
wherein said second pump controller and second power supply are disposed
outside of said transport section.
7. A portable artificial-heart drive system according to claim 1, wherein
said purge solution circulator comprises:
a reservoir to store the purge solution;
a purge solution circulating pump,
a filter, and
a purge solution circulation route for connecting said reservoir, said
purge solution circulation pump and said filter among one another,
wherein said purge solution circulating pump circulates the purge solution
between said reservoir and said blood seal,
wherein said filter filters the purge solution,
wherein said purge solution circulator circulates the purge solution inside
said blood pump via said filter.
8. A portable artificial-heart drive system according to claim 7, wherein
said purge solution comprises:
a solution selected from the group consisting of pure water and
physiological saline, and
a disinfectant for sterilizing the purge solution.
9. A portable artificial-heart drive system according to claim 7, wherein
said purge solution circulator further comprises a bypass channel wherein
said reservoir has an inlet and an outlet, wherein said outlet is in
communication with said purge solution circulating pump, wherein said
purge solution circulating pump is in communication with said filter,
wherein said inlet is in communication with said bypass channel and
wherein said bypass channel is in communication with said filter.
10. A portable artificial-heart drive system according to claim 7, wherein
said purge solution circulating pump, said filter, and said reservoir are
combined into a unit.
11. A portable artificial-heart drive system according to claim 7, wherein
said reservoir comprises a flexible material.
12. A portable artificial-heart drive system according to claim 7, wherein
said purge solution circulator further comprises at least one pressure
sensor disposed at one of an inlet and outlet of said filter.
13. A portable artificial-heart drive system according to claim 7, wherein
said purge solution circulator further comprises at least one temperature
sensor.
14. A portable artificial-heart drive system according to claim 1, wherein
said controller comprises a kinetic load detecting mechanism to detect the
kinetic load of the patient using said portable drive system, and wherein
said controller controls the operating condition of said blood pump
according to the output from said kinetic load detecting mechanism.
15. A portable artificial-heart drive system according to claim 14, wherein
said kinetic load detecting mechanism detects a moving speed of said
transport section.
16. A portable artificial-heart drive system according to claim 14, wherein
said kinetic load detecting mechanism detects a load change of said motor
portion in said blood pump, the load change synchronizing with the heart
rate of the living body.
17. A portable artificial-heart drive system according to claim 14, wherein
said kinetic load detecting mechanism comprises:
a speed detector to detect a speed of said transport section, and
a heart rate detector to detect the heart rate of the patient.
18. A portable artificial-heart drive system according to claim 16, wherein
said kinetic load detecting mechanism detects a change in current value of
said motor portion in said blood pump, and detects the kinetic load of the
patient based on an estimated heart rate.
19. A portable artificial-heart drive system according to claim 16, wherein
said kinetic load detecting mechanism detects a change in number of
revolutions of said motor portion in said blood pump, and detects the
kinetic load of the patient based on an estimated heart rate.
20. A portable artificial-heart drive system according to claim 1, wherein
said display displays operating states of said said portable
artificial-heart drive system, and provides an alarm when deviation from a
set value arises.
21. A portable artificial-heart drive system according to claim 1, wherein
said communication interface exchanges information between the patient and
one of a hospital and a doctor.
22. A portable artificial-heart; drive system according to claim 1, further
comprising:
a connecting terminal arranged on a belt-like stomach band worn by the
patient; and
a motor cable connecting said blood pump, said connecting terminal and said
pump controller,
wherein said connecting section comprises first and second purge tubes for
connecting said blood pump and said purge solution circulator, said motor
cable.
23. A portable artificial-heart drive system according to claim 22, wherein
said connecting section further comprises a bellow-like protective tube,
wherein said first and second purge tubes and said motor cable are
helically shaped, and said bellows-like protective tube covers said first
and second purge tubes and said motor cable, so that said connecting
section is expandable.
24. A portable artificial-heart; drive system according to claim 23,
wherein an expansion amount of said protective tube is smaller than that
of said first and second purge tubes and said motor cable in said
connecting section.
25. A portable artificial-heart drive system according to claim 23, wherein
said protective tube comprises a plurality of circular rings embedded
therein.
26. A portable artificial-heart drive system according to claim 22, wherein
said first and second purge tubes comprise a valve mechanism for blocking
the flow of the purge solution.
27. A portable artificial-heart drive system according to claim 26, wherein
said valve mechanism is disposed between said connecting terminal and said
blood pump.
28. A portable artificial-heart drive system according to claim 22, wherein
said connecting terminal comprises at least one system of pump controller
and a power supply.
29. A portable artificial-heart drive system according to claim 1, wherein
said skin button section comprises a carbon fiber structure having many
air spaces on the surface thereof, and is implanted inside the epidermis F
of the patient.
30. A portable artificial-heart drive system according to claim 1, wherein
said transport section comprises a mount having a wheel for portably
bearing said system drive section located outside the body, and is
automatically and manually carried along with the patient.
31. A portable artificial-heart drive system according to claim 30, wherein
said transport section comprises a waterproof and anti-contamination
structure for preventing contaminants from entering said system drive
section.
32. A portable artificial-heart drive system according to claim 30, wherein
said transport section comprises a shock-absorbing structure so that
vibrations and shocks caused by movement are not transmitted to said
system drive section.
33. A portable artificial-heart drive system according to claim 1, wherein
said power supply comprises a plurality of power sources, wherein said
plurality of power sources comprises at least one of a commercial AC power
source, an automobile-installed power source, and a secondary battery
built in said transport section, wherein said power supply comprises a
switch to select at least one of said plurality of sources.
Description
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to medical equipment for use in a human body,
and more particularly, to a portable drive system for an artificial heart,
and to a portable drive system for an artificial heart that has high
safety, high reliability, and reduced size and weight, and is easy to use,
thereby expanding the range of life.
2. Background Art
Since a conventional drive system for an artificial heart is large and
difficult to move, the life of a patient using the artificial heart has
been limited to the inside of a hospital. While attempts have recently
been made to reduce the size of an artificial-heart drive system, a system
to be used in life outside a hospital is not yet in actual use in terms of
size and safety.
An artificial-heart drive system is large, and therefore, the life of the
patient is limited to the inside of the hospital. In terms of improved
quality of life for the patient and medical rehabilitation, it is
preferable that the life of the patient be not limited and that the
patient can live a life at home. For that purpose, it is necessary to
reduce the size of attendant fixtures of the artificial heart, to improve
reliability, and to establish safeguards.
Accordingly, the present invention has been made in view of such
circumstances, and has as an object the provision of a drive system for an
artificial heart that does not limit the life of a patient having an
implanted artificial heart with much regard for high safety.
DISCLOSURE OF INVENTION
A portable drive system for an artificial heart according to the present
invention includes a blood pump 1 to be implanted in a body, a system
drive section 45 for controlling the blood pump 1 from outside the body,
and a connecting section 70 for connecting the blood pump 1 or purge
solution circulating means and the system drive section 45. The connecting
section 70 penetrates through the epidermis F of a patient.
The system drive a purge solution circulator 20 or a purge solution
circulating means for supplying by circulating solution (hereinafter
referred to as purge solution) to a contact surface of a blood seal 18
located inside the blood pump 1 in order to maintain the shaft sealing of
a rotation shaft 13 in the blood pump 1 with respect to blood, a pump
controller 30 pump control means for electrically controlling the drive of
the blood pump 1 via. a motor cable 71, a display 40 or display means for
displaying operation states of the aforementioned means and data thereon,
a communication interface 50 or communication means for exchanging
information with the outside, a power supply 33 or power supply means for
supplying electric power to the aforementioned means, a controller 100 or
control means for controlling the aforesaid means, and a transport section
60 for bearing the system drive section 45 portably.
The blood seal 18 includes a contact seal, such as a mechanical seal and an
oil seal.
The connecting section 70 includes purge tubes 24 and 25 for connecting the
blood pump 1 and the purge solution circulator 20 and causing the purge
solution to circulate between the purge solution circulator 20 and the
contact surface of the blood seal 18, and the motor cable 71 for supplying
electric power to the blood pump 1, a connecting terminal 80 for
connecting internally embedded parts and externally exposed parts of the
purge tubes 24 and 25 and the motor cable 71, a skin button section 90 for
causing parts of the purge tubes 24 and 25 and the motor cable 71, which
penetrate through the epidermis F, to firmly adhere to the epidermis F, a
valve mechanism 75 for blocking the flow of the purge solution, and a
protective tube 72 for covering the externally exposed parts of the purge
tubes 24 and 25 and the motor cable 71.
The system drive section 45 has a plurality of pump controller 30 and a
plurality of power supply 33, and at least one pair of the pump controller
30 and the power supply means 33 are located inside or near the connecting
terminal 80.
The system drive section 45 further has a mechanism for supplying power
only to the above pump controller 30 when the quantity of electricity
remaining in the power supply 33 falls below a specified value.
The purge solution circulator 20 includes a purge solution circulating pump
22 for circulating the purge solution that circulates inside the blood
pump 1 and a disinfectant to be added in the purge solution, a flexible
reservoir 21 for storing the purge solution, a filter 23 for filtering the
purge solution, and a bypass channel 26 located on the flow channel of the
purge solution.
Also located on the flow channel of the purge solution are detectors for
detecting the temperature and pressure of the purge solution, and the
valve mechanism 75 for preventing the outflow of the purge solution.
The controller 100 has a kinetic load detecting mechanism 31 for detecting
the kinetic load needed for the movement of the transport section 60, and
has the function of controlling the number of revolutions of the blood
pump 1 in accordance with the output from the detecting mechanism. The
controller 100 also has the self diagnosis function of monitoring output
signals from the constituents of the portable drive system and detecting
the abnormal conditions of the constituents, and has means for
transmitting control signals to the aforementioned means.
The display 40 has a monitor for displaying information obtained from
output signals from the controller 100, and a control button 42 for
changing operating parameters of the constituents.
The communication interface 50 has a transmission function of transmitting
information about the operating state of the portable artificial-heart
drive system to a control center of the hospital or the like, and a
receive function of receiving instructions from the control center.
The connecting section 70 has an expandable structure, and a structure for
reinforcing the protective tube 72 to prevent breakage.
The skin button section 90 has a structure in which the connecting section
70 firmly adheres to the epidermis F to prevent percutaneous infection and
separation due to the movement of the body.
The portable artificial-heart drive system according to the present
invention operates as follows.
First, according to the invention claimed in claim 1, a system drive
section, which includes purge solution circulator for maintaining the
shaft sealing of a rotation shaft of a blood pump with respect to blood,
pump controller for electrically controlling the drive of the blood pump,
display for displaying operating states of constituents of the portable
artificial-heart drive system and inputting the conditions of the
constituents, power supply for supplying electric power to the means,
communication interface for exchanging information with the outside, and
controller for controlling the means, is constructed in a compact size,
mounted on a movable transport section, and connected to the blood pump
implanted in the body via a connecting section. This makes it possible to
obtain a portable artificial-heart drive system that is small-sized,
lightweight, and movable, and to expand the life range of the patient.
According to the invention claimed in claim 2, a mechanical seal or an oil
seal is used as a blood seal. By supplying the purge solution by
circulating to a contact surface of the blood seal by the purge solution
circulator, the lubrication of the contact surface is stabilized, and the
sealing ability is maintained for a long time. Furthermore, since the
contact surface of the blood seal is cooled, the contact surface is not
damaged by heat denaturation of protein ingredients of the blood that
enter the contact surface by diffusion. Still furthermore, since the blood
ingredients that enter in the purge solution by diffusion are diluted and
discharged outside the blood pump by a large amount of purge solution, the
rotation shaft does not stick. The purge solution only circulates in the
purge solution channel, and leaks from the blood seal portion in very
small amounts.
According to the invention claimed in claims 3 and 4, when the quantity of
electricity remaining in a battery built in the power supply falls below a
specified value, power is preferentially supplied to the backup pump
controller. This makes the driving time of the portable artificial-heart
drive system longer, and thereby improves safety.
According to the invention claimed in claims 5 and 6, the portable
artificial-heart drive system has a plurality of systems of pump
controller and power supply serving as basic functions for the operation
of the blood pump, which improves the safety of the portable
artificial-heart drive system. Moreover, since at least one system of pump
controller and power supply are separated from the transport section, and
located near the surface of the patient's body, the blood pump is
prevented from stopping even when serious trouble, such as the breakage of
the transport section, or the cutoff of the connecting section, occurs.
Therefore, the safety of the portable artificial-heart drive system is
further improved.
According to the invention claimed in claims 7 and 8, since a filter using
an ultrafilter membrane is located on the channel in which the purge
solution circulates, it is possible to always keep the purge solution
clean, to prevent the blood from coagulating at the seal and the bearing
in the blood pump of the artificial heart, and simultaneously, to keep the
purge solution sterilized and detoxified. By adding a disinfectant in the
purge solution, the insides of the reservoir and the ultrafilter can be
disinfected. Thereby, the purge solution that flows in the blood pump of
the artificial heart is physically and chemically disinfected, and double
safeguards are provided.
According to the invention claimed in claim 9, a cross flow circulation
route having a bypass channel is formed to prevent the ultrafilter from
clogging, and provides the following functions.
1. Since air in the filter is automatically removed via the bypass channel,
the filter does not cause malfunction due to an air trap.
2. Since the bypass channel serves as a safety valve, the increase in
pressure of the purge solution can be kept at a fixed value or less.
3. Because of the cross flow circulation route, the flow rate of the purge
solution flowing in the purge solution circulator located outside the body
increases by an amount corresponding to the flow rate of the purge
solution passing through the bypass channel, and the radiation effect of
the purge solution improves.
According to the invention claimed in claim 10, the reservoir, the purge
solution circulating pump, and the ultrafilter may be combined into a unit
so as to make periodical replacement thereof considerably easy and clean.
According to the invention claimed in claim 11, since the reservoir is made
flexible, it can flexibly respond to its change in capacity with the
outflow of purge solution via the contact surface of the blood pump, in
altitude with the movement of the transport section, vibrations and the
like, whereby the circulation of purge solution can be kept safe.
According to the invention claimed in claim 12, sensors for detecting the
pressure are disposed at the entrance and exit of the filter to monitor
the pressure, which makes it possible to detect the choking of the purge
solution circulating circuit, the clogging of the filter, and the like.
According to the invention claimed in claim 13, a sensor for detecting the
temperature is disposed on the purge tube to measure the temperature of
the purge solution, which provides the following functions.
1. The safety of the portable artificial-heart drive system can be improved
by controlling the temperature of the purge solution by changing the
amount of the purge solution to be circulated so that the temperature does
not reach the heat denaturation temperature of protein ingredients of
blood.
2. A portable artificial-heart drive system that imposes little load on a
living body can be constructed by controlling the flow rate of the purge
solution so as to reduce the change of amount of heat between the living
body and the portable artificial-heart drive system.
According to the invention claimed in claims 14 to 19, a mechanism for
detecting the kinetic load of the patient is disposed to control the
number of revolutions of the blood pump in accordance with the load,
whereby the quality of life of the patient can be improved.
The kinetic load can be easily detected by calculating the moving speed of
the transport section by a rotary detector disposed on a wheel of the
transport section. Moreover, the number of revolutions of the blood pump
can be changed in accordance with the heart rate of the living body to be
estimated from the load change cycle of the blood pump that synchronizes
with the heart rate. While these methods may be separately used, the use
of both methods makes it possible to distinguish the change in heart rate
due to the kinetic load and the change in heart rate due to medical
strain, excitation or the like, and to thereby control the blood pump more
closely. This can improve the quality of life of the patient.
According to the invention claimed in claims 20 and 21, the constituents of
the artificial heart may be provided with sensors, and the operating
states of the constituents are always displayed and monitored by using the
display. When the value obtained from the sensor is compared with and
deviates from the preset value, an alarm is given, and detailed
information is displayed on the display. Furthermore, the information is
transferred to the external control center via the communication
interface, and appropriate instructions are transferred back from the
external control center, which ensures that the patient has a safe life
outside the hospital.
According to the invention claimed in claim 22, the internally embedded
part and the externally exposed part of the connecting section are
connected by the connecting terminal, and the connecting terminal is fixed
to a belt-like stomach band. Therefore, external force caused by movement
of the body is not directly transmitted to the internally embedded part of
the connecting section. Moreover, since the connecting section can split
at the connecting terminal, easy replacement and maintenance of the
transport section are possible.
According to the invention claimed in claims 23 to 25, the connecting
section is expandable and does not hinder the activities of the patient.
Moreover, the purge tubes and the motor cable are prevented from breaking
by being covered with a reinforced protective tube. Since the expansion
amount of the protective tube is smaller than that of the purge tubes and
the motor cable, the purge tubes and the motor cable are prevented from
tensile fracture.
According to the invention claimed in claims 26 and 27, if the circulation
of purge solution stops due to trouble or the like of the purge solution
circulator, the valves disposed in the purge tubes are automatically
closed, so that the purge solution is prevented from flowing out on the
back of the blood seal in the blood pump. Therefore, it is possible to
safely maintain the shaft sealing action of the blood seal. Considering
that the externally exposed part of the portable artificial-heart drive
system has a high risk of being damaged, the valve mechanism is placed in
the internally embedded part to further improve the safety.
According to the invention claimed in claim 28, it is preferable that one
system of the pump controller and the power supply be placed between the
connecting terminal and the internally embedded part whose risk of damage
is low.
According to the invention claimed in claim 29, a skin button section
formed of carbon fibers having many pores on their surfaces is disposed in
a part of the internally embedded part of the connecting section that
penetrates through the epidermis, so that the skin button section firmly
adheres to the epidermis, and percutaneous infection is avoided.
According to the invention claimed in claims 30 to 32, the means disposed
outside the human body are carried on the transport section and can be
transported along with the human body. The means also have a waterproof
and anti-contamination structure, and a structure for absorbing vibrations
and impacts caused by transportation, which improves the safety of the
transport section.
According to the invention claimed in claim 33, the power supply of the
transport section may be driven by AC power source, a power source
installed in an automobile or the like, or a second battery built in the
transport section, and this does not limit the scope of activities of the
patient.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a structural diagram of a portable drive system for an artificial
heart according to an embodiment of the present invention,
FIG. 2 is an enlarged sectional view of a blood pump shown in FIG. 1,
FIG. 3 is an explanatory view showing a state in which the portable
artificial-heart drive system shown in FIG. 1 is implanted in a living
body,
FIG. 4 is an explanatory diagram of a pump controller shown in FIG. 1,
FIG. 5 is an explanatory view of a kinetic load detecting mechanism shown
in FIG. 1,
FIG. 6 is an explanatory diagram of a power supply shown in FIG. 1,
FIG. 7 is an explanatory diagram of a purge solution circulator shown in
FIG. 1,
FIGS. 8A-8C are explanatory views of display shown in FIG. 1;
FIG. 9 is an explanatory view of a connecting terminal shown in FIG. 1,
FIG. 10 is an enlarged sectional view of a skin button section shown in
FIG. 1, and
FIG. 11 is an enlarged sectional view of a connecting section shown in FIG.
1.
BEST MODE FOR CARRYING OUT THE INVENTION
A description will be given of an embodiment of the present invention which
applies to an artificial heart.
FIG. 1 is a structural diagram of a portable drive system for an artificial
heart according to an embodiment of the present invention. In the figure,
the portable artificial-heart drive system includes a blood pump 1 to be
implanted in a body, a system drive section 45 for controlling the blood
pump 1 from outside the body, and a connecting section 70 for connecting
the blood pump 1 and the system drive section 45.
The portable artificial-heart drive system further includes the system
drive section 45 that is composed of a purge solution circulator 20 for
supplying by circulating purge solution to a contact portion of a blood
seal 18 located inside the blood pump 1 in order to prevent blood from
entering a bearing 19 of a rotation shaft 13 in the blood pump 1, a pump
controller 30 for electrically controlling the drive of the blood pump 1
via a motor cable 71, a display 40 for displaying an operation state of
the aforementioned means and data thereon, a communication interface 50
for exchanging information with the outside, a power supply 33 for
supplying electric power to the aforementioned means, a controller 100 for
controlling the aforesaid means, and a transport section 60 for bearing
the system drive section 45 portably.
The connecting section 70 comprises purge tubes 24 and 25 for connecting
the blood pump 1 and the purge solution circulator 20 in the system drive
section 45, the motor cable 71 for connecting the blood pump 1 and the
pump controller 30, a connecting terminal 80 for connecting an internally
embedded part and an externally exposed part of the connecting section 70,
and a skin button section 90 for causing the internally embedded parts of
the purge tubes 24 and 25 and the motor cable 71 to firmly adhere to the
epidermis F of a patient. The connecting terminal 80 has a pump controller
30 and a power supply 33 for backup.
In this artificial heart, if the heart pump stops, the life of the patient
may be seriously affected. On the other hand, even if advanced functions
of the communication interface 50, a kinetic load detecting mechanism 31
and the like temporarily stop, it does not directly threaten the life of
the patient. Regarding the blood seal 18 of the rotation shaft 13 in the
blood pump 1, unless the purge solution is lost on the back of the blood
seal 18, problems do not arise over the following a few hours even when
the circulation of the purge solution stops. Accordingly, in this system,
the pump controller 30 and the power supply 33 serving as basic functions
for the rotation of the blood pump 1 need added safety. The portable
artificial-heart drive system is equipped with both these basic functions,
which improve the safety.
If the connecting section 70 is cut off or the system drive section 45
itself is badly damaged, however, such added safeguards provided in the
system drive section 45 are useless. In view of this point, the pump
controller 30 and the power supply 33 for backup are placed near the
surface of the patient's body where the risks of the aforesaid accidents
are low.
FIG. 2 shows an example of the blood pump 1, and FIG. 3 shows a case in
which the portable artificial-heart drive system is implanted in the human
body.
The blood pump 1 includes a pump base section 10 having a cylindrical motor
portion 11, and a pump section 12 connected to the pump base section 10.
The pump section 12 includes a pump vane 14 to be driven via the rotation
shaft 13 extending from the motor portion 11, and a casing 15 connected to
the pump base section 10 so as to cover the pump vane 14. Blood in the
left ventricle A flows into the casing 15 from an inlet 16 formed at the
end of the casing 15, is supplied with energy by the pump vane 14 in the
casing 15, and is discharged to the aorta B via an outlet 17 formed on the
side of the casing 15 and an artificial blood vessel C.
The blood seal 18 being an end-face contact type (hereinafter referred to
as mechanical seal) is located between the pump base section 10 and the
pump vane 14 so that it prevents the bearing 19 of the rotation shaft 13
from adhesion due to the entry of a blood ingredient. Moreover, an inlet 8
and an outlet 9 for the purge solution are formed in the pump base section
10, and connected to the purge solution circulating device, which will be
described later, via the purge tubes 24 and 25. The purge solution is
circulated inside the mechanical seal 18 by the purge solution circulator
20, and operates to lubricate and cool the contact surface of mechanical
seal, and to remove by diffusion very small quantities of blood
ingredients that enter the purge solution, whereby the contact surface of
the mechanical seal 18 and the bearing 19 are always kept clean.
While a centrifugal pump is used as the blood pump 1 in this example, an
axial-flow pump or a mixed flow pump are also available. Furthermore, the
blood seal 18 is not limited to the mechanical seal, and other contact
seals, such as an oil seal, may be available.
The system drive section 45, which includes the purge solution circulator
20 for supplying purge solution to the mechanical seal 18 located inside
the blood pump 1, the pump controller 30 for electrically controlling the
drive of the blood pump 1 via the motor cable 71, the display 40 for
displaying the operation states of the aforementioned means and data
thereon, the communication interface 50 for exchanging information with
the outside, the power supply 33 for supplying electric power to the
aforementioned means, and the controller 100 for controlling the
aforementioned means, is constructed inside a compact housing 61, and
mounted on the manual transport section 60 having wheels 62 and a handle
63.
While the transport section 60 in this example is shaped like a handcart,
it may take any shape that is suited for the condition and living
environment of the patient, for example, a wheel chair or a bag.
Furthermore, the transport section 60 may be a motor-driven type in which
the wheels 62 are equipped with a motor.
FIG. 4 is a structural diagram of the pump controller 30.
The controller 100 is formed of a one-board microcomputer or the like that
includes an arithmetic unit 101, a memory 102, and various types of
interfaces 103. Output signals, which are input to the arithmetic unit 101
from sensors in the above means via an AID converter 104, are processed
according to a control program stored in a ROM of the memory 102, and the
calculation result is output via a D/A converter 105. Moreover, data is
exchanged with arithmetic units 101 and 1101 of the constituents via the
interfaces 103 and 1103. The data is stored in a RAM of the memory 102,
and displayed by the display 40.
The blood pump 1 is usually controlled by the controller 100. The control
means 100 calculates a position signal corresponding to the rotational
position of a rotor 106 in the pump control. The rotation of the rotor 106
is detected based on the output from a Hall sensor 108 located inside the
motor portion 11 of the blood pump 1, and the arithmetic unit 101 of the
controller 100 performs calculation so that the number of revolutions of
the blood pump 1 is constant. Power suppliers 107 inside the connecting
terminal 80 supply stator windings 109 of the motor with electric power
according to the position signal.
While the number of revolutions is controlled by using the Hall sensor 108
in this embodiment, the driving can be performed without a sensor, and the
control method is not limited to constant revolution control.
The backup pump controller 30 is located in the connecting terminal 80, and
the controller 100 and the backup pump controller 30 mutually monitor
their arithmetic units 101 and 1101 via the interfaces 103 and 1103. For
example, when trouble occurs to the arithmetic unit 101 of the controller
100, the control of the blood pump 1 is switched to the backup pump
controller 30, and the arithmetic unit 101 of the controller 100 is reset
via the interface 103. After the arithmetic unit 101 of the controller 100
is reset and returned to a normal state, the control of the heart pump is
transferred to the controller 100, and the backup pump controller 30
monitors only the arithmetic unit 101 of the controller 100. Conversely,
when trouble of the arithmetic unit 1101 of the backup pump controller 30
is detected, the backup pump controller 30 is reset.
While the pump controller 30 and the power supply 33 of this example are
provided in two systems, they are not limited to two systems, and may be
provided in more systems.
The kinetic load detecting mechanism 31 is formed of a rotation detector 32
mounted on the wheel 62 of the transport section 60. The controller 100
calculates the speed of travel of the portable artificial-heart drive
system based on a signal from the rotation detector 32, and increases or
decreases the number of revolutions of the motor in the blood pump 1 in
response to the speed of travel. Since the momentum of the patient can be
easily detected, the quality of life of the patient can be improved.
Furthermore, control may be exerted by calculating the heart rate based on
the change in load of the motor in the blood pump 1 depending on the heart
beat of the living body and increasing or decreasing the number of
revolutions of the motor in the blood pump 1 in response to the change in
heart rate.
FIG. 5 explains the method of estimating the heart rate of the living body,
and shows the characteristics in a case in which the centrifugal pump
shown in FIG. 2 is controlled so that the number of revolutions is
constant.
In this blood pump 1 that removes blood from the left ventricle A of the
living body and sends the blood to the aorta B, the load on the motor
portion 11 substantially varies with the change in pressure inside the
left ventricle A owing to the heart beat of the living body. For example,
when the difference between the internal pressure of the left ventricle A
corresponding to the inflow pressure of the blood pump 1 and the pressure
in the aorta B corresponding to the outflow pressure changes with the
heart beat between P1 and P2, the flow rate of the blood pump 1 changes
between Q1 and Q2. When the flow rate of the blood pump 1 changes between
Q1 and Q2, the current value of the blood pump 1 also changes between I1
and I2. Therefore, the heart rate of the living body can be estimated by
monitoring the cycle of the change in current value. Although not shown in
the figure, a similar characteristic is provided in a case in which the
blood pump 1 is controlled so that the current value is constant, and the
heart rate of the living body can be estimated based on the change in
number of revolutions of the blood pump 1.
Since the operating point of the blood pump 1 is automatically lifted or
lowered according to the kinetic load of the patient, it is possible to
improve the quality of life of the patient. The above-mentioned control
methods may be used separately or simultaneously.
Since the detection means can be achieved in a considerably simple
structure, it is possible to limit the malfunction and failure, and to
thereby improve the quality of life of the patient.
FIG. 6 is a structural diagram of the power supply 33.
The power supply 33 includes a power supply control section 34 for
controlling the switching of power sources to be used and the charge and
discharge of built-in batteries 35, the plural batteries 35 formed of
nickel hydrogen secondary batteries or lithium ion secondary located in
the system 36, and the like, and it is located in the system drive section
45 and the connecting terminal 80. In a case in which the use of an
external power source 37, such as AC power source or an
automobile-installed power source, is possible, the portable drive system
is driven by the external power source 37, and simultaneously, the plural
built-in batteries 35 are charged by the charger 36. When the external
power supply 37 cannot be used, the plural batteries 35 in the system
drive section 45 are sequentially used. A battery 35 in the connecting
terminal 80 is used when the power supply 33 in the system drive section
45 cannot be used, for example, when the system drive section 45 is
damaged. In normal operations, the power supply 33 in the system drive
section 45 is used. Furthermore, when the quantity of electricity
remaining in the batteries 35 in the system drive section 45 falls below a
specified value, the supply of power to the means that constitute the
system drive section 45 is stopped, and power is supplied only to the
backup pump controller 30 in the connecting terminal 80, whereby the
driving time of the portable drive system is extended.
The built-in batteries 35 are provided with battery control circuits 38,
respectively, each of which monitors the remaining quantity in the battery
35, the number of times of charge and discharge, the voltage, and the
like. The power supply control section 34 receives the aforesaid data from
the battery control circuits 38, and sequentially and selectively controls
the charge and discharge of the batteries.
The output from sensors 39, which are provided for the batteries to detect
the temperatures thereof, is monitored by the controller 100, thereby
preventing the combustion and explosion resulting from extraordinary heat
generation of the batteries 35.
The controller 100 and the arithmetic unit 1101 of the power supply 33
mutually exchange information about operations of their constituents and
monitor the operation states thereof via the interfaces 103 and 2103. For
example, the arithmetic unit 1101 of the controller 100 receives, from the
arithmetic unit 101 of the power supply 33, information, such as the type
of power source to be used, the remaining quantity and the number of times
of charge and, discharge of the batteries 35, the voltage, and the
temperature of the batteries 35, and it makes a judgement on the
operations. The information is displayed on the display 40. Furthermore,
when the arithmetic unit 2101 of the power supply control section 34 is
out of order, it is reset via the interface2103. The configuration of the
controller 100 is common to the aforementioned one, and therefore, a
description thereof is omitted.
FIG. 7 is a structural diagram of the purge solution circulator 20.
The purge solution circulator 20 supplies purge solution to the contact
surface of the aforementioned mechanical seal by circulating it in order
to maintain the shaft sealing of the rotation shaft 13 in the blood pump 1
with respect to blood. Purge solution with disinfectant added therein is
caused by a purge solution circulating pump 22, which circulates the purge
solution, to pass from a reservoir 21 for storing the purge solution
through a filter 23 for filtering the purge solution. One part of the
purge solution passes through the purge tube 24, flows into the blood pump
1 implanted in the body, reaches the contact surface of the mechanical
seal, and then, returns to the reservoir 21 via the purge tube 25. The
other part of the purge solution flowing out of the filter 23 passes
through a bypass channel 26 and returns to the reservoir 21.
Moreover, valve mechanisms 75 are located on the purge tubes 24 and 25. The
valve mechanisms 75 close the purge tubes 24 and 25 the moment the
circulation of the purge solution stops, and holds the purge solution in
the blood pump 1, thereby maintaining the function of the blood seal 18.
A protein ingredient of blood, which enters the purge solution by diffusion
via a lubricating thin film on the contact surface of the mechanical seal
in the blood pump 1, is filtered by the filter 23 located on the channel
where the purge solution circulates. Therefore, the purge solution is
always kept clean, and the bearing 19 of the rotation shaft 13 in the
blood pump 1 can be prevented from seizure. Moreover, when an ultrafilter
membrane is used as the filter 23, it is possible to remove bacteria,
viruses, and bacteriotoxin, and to sterilize and detoxify the purge
solution.
Furthermore, there is a fear that bacteria or viruses will enter the purge
solution due to the exchange of purge solution or the breakage of the
transport section 60, and it is preferable that the purge solution itself
have a sterilizing action. Therefore, chlorination using hypochlorous acid
or the like is used as a means of disinfecting the purge solution. The
hypochlorous acid can sterilize almost all kinds of bacteria and viruses
in low concentration, and combines with an organic matter in the living
body to form an organochilorine compound, thereby performing
detoxification. In addition, the reservoir 21 and the filter 23 are
disinfected by adding a disinfectant in the purge solution.
Thus, the purge solution that flows in the blood pump 1 of the artificial
heart is disinfected physically and chemically, which achieves double
safeguards.
In order to remove bacteria, viruses and bacteriotoxin, and furthermore, to
remove fibrinogen that causes the adhesion of the bearing, the pore size
of the filter 23 using an ultrafilter membrane is set at a molecular
weight of 340,000 or less.
Furthermore, the cross flow circulation route in which the bypass channel
26 is formed to prevent the clogging of the filter 23 serves three
functions as follows.
Firstly, when the ultrafilter membrane 23 is of the hollow fiber type,
since air in the fiber is automatically removed through the bypass channel
26, the filter 23 does not cause malfunction due to an air trap.
In a case in which the connecting section 70 for connecting the blood pump
1 in the artificial heart and the system drive section 45 outside the body
is blocked by external force (e.g., stepped on or caught in a door), the
bypass channel 26 in the purge solution circulator20 having the cross flow
circulation route functions as a safety valve in such an emergency, and
keeps the increase in pressure of the purge solution less than a
predetermined value, thereby preventing the purge solution circulator from
breaking.
In the purging circuit having a cross flow circulation route, the flow rate
of the purge solution flowing in the purge solution circulator located
outside the body increases by an amount corresponding to the flow rate of
the purge solution passing through the bypass channel 26. Since the purge
solution is cooled by heat dissipation that results from the temperature
difference between the purge solution and outside air, the radiation
effect of the purge solution improves as the flow rate of the purge
solution increases.
Furthermore, since the purge solution decreases because it leaks from the
contact surface of the mechanical seal in a very small quantity, there is
a need to replace the reservoir 21 at fixed periods. Moreover, if protein
adheres to the filter 23, it may cause the proliferation of bacteria, and
therefore, there is also a need to replace the filter 23 at fixed periods.
The reservoir 21, the purge solution circulating pump 22, and the filter
23 using an ultrafilter membrane may be combined into a unit so as to make
periodical replacement considerably easy and clean.
Suited as the purge solution circulating pump 22 is a small-sized positive
displacement pump that has high efficiency and high reliability, does not
need a seal, and can be disinfected. In the figure, a roller pump is used,
and it has a structure in which purge solution is sent out from a pipe,
where it flows, by stroking the pipe from the outside. The roller pump is
preferable because only the inner side of the pipe is in contact with the
purge solution. Though not shown in the figure, other small pumps, such as
a diaphragm pump and a gear pump, may be used.
Sensors 27a and 27b for detecting the pressure are mounted at the entrance
and exit of the filter 23, and the outputs from the sensors 27a and 27b
are monitored by the controller 100 via AID converter 104, whereby the
choking of the purge solution circulating circuit, the clogging of the
filter 23, and the like are monitored.
Furthermore, a sensor 28a for detecting the temperature of the purge
solution, which circulates from the blood pump 1 to the purge solution
circulator 20, is mounted on the purge tube 25, and the operating
conditions of the purge solution circulating pump 22 are controlled so
that the temperature of the purge solution does not reach the heat
denaturation temperature of the protein ingredients in the blood. In this
embodiment, the arithmetic unit 101 of the controller 100 calculates the
operating conditions, and the arithmetic unit 3101 of the purge solution
circulator control section 110 controls the purge solution circulating
pump 22 according to the instructions from the controller 100 via AID
converter 3104.
Still furthermore, a sensor 28b for detecting the temperature of the purge
solution, which circulates from the purge solution circulator 20 to the
blood pump 1, is mounted on the purge tube 24 to compare the temperatures
of the purge solution that flows into the blood pump 1 and the purge
solution that flows out therefrom, whereby the heat flow between the
living body and the portable artificial-heart drive system can be grasped.
By controlling the operating conditions of the purge solution circulating
pump 22 so as to reduce the heat flow, it is possible to construct a
portable drive system for an artificial heart that imposes little load on
the living body.
The operating conditions of the purge solution circulator 20 can be grasped
in more detail by adding a flow rate sensor, a blood sensor and the like
besides the pressure sensor and the temperature sensor.
The reservoir 21 containing purge solution is shaped like a flexible bag,
so that it can respond to its change in capacity with consumption of purge
solution, in altitude with the movement of the transport section 60, and
the like.
Moreover, the reservoir 21 is provided with a sensor 29 for detecting the
volume of purge solution, and the output from the sensor 29 is monitored
by the controller 100, thereby monitoring the leakage of the purge
solution.
The controller 100 monitors the arithmetic unit 3101 of the purge solution
circulator control section 110 via the interface3103, and resets it when
an error occurs thereto.
The display 40 includes a display section 41 for displaying information,
and an input means (not shown) for switching displayed information and
inputting data. The display section 41 always displays information about
the operations of the constituents of the artificial heart that is
processed by the controller 100. When the operation information deviates
from set values, an alarm is given, and detailed information, such as a
countermeasure, is displayed on the display section 41.
FIGS. 8(a) to 8(c) show examples of displays on the display section 41.
FIG. 8(a) shows a usual display state. The uppermost section indicates the
number of days the present portable artificial-heart drive system has been
in use. The left column indicates the outer temperature, the heart rate,
and the operating state of the connecting terminal 80 in that order from
the top. The right column indicates the states of the blood pump 1, the
purge solution circulator 20, and the battery 35, in that order from the
top. The bottom right section indicates the charge or discharge, and the
use of the external power source 37. Usually, basic information about the
operations mentioned above is displayed, and more detailed information
about the operations of the constituents may be displayed through the
input means.
FIG. 8(b) shows detailed operation states of the purge solution circulator
20. The upper section indicates the operation states of the blood pump 1,
the reservoir 21, the purge solution circulating pump 22, and the filter
23 that constitute the purge solution circulator 20, and the purge tubes
24 and 25. The lower section indicates, from the left, the outer
temperature, the operation state of the arithmetic unit 101 in the purge
solution controller 100, and the temperature of the purge solution.
When abnormal conditions are encountered, the message shown in FIG. 8(c) is
displayed, and details of the abnormal conditions may be displayed by
switching through the input means (not shown).
In addition, operating parameters may be changed through the input means.
The communication interface 50 has a connecting terminal for connection to
a telephone line, and- can make connection to a computer in a hospital or
the like. The portable artificial-heart drive system can be controlled and
monitored by a computer in the hospital. By incorporating the mobile
communication interface 50, such as a portable telephone, information
about the portable artificial-heart drive system is appropriately
transferred to the hospital or the like, and appropriate instructions are
transferred back. Therefore, the safety of life of the patient outside the
hospital is further increased.
FIG. 9 shows an example of the connecting terminal 80.
The connecting terminal 80 connects the internally embedded part and the
externally exposed part of the connecting section 70. The connecting
terminal 80 is fixed to a belt-like stomach band 81. Since the externally
exposed part of the connecting section 70 is expandable, external, force
caused by movement of the body is not directly transmitted to the
internally embedded part of the connecting section 70.
Furthermore, the connecting terminal 80 has a display section 41 on which
information, such as the number of revolutions of the motor in the blood
pump 1 and the amount of electricity in the battery, is sequentially
displayed by switching using a control button 42. When an error occurs, it
is announced by the illumination of an error indicator 43 and an alarm.
Still furthermore, the pump controller 30 and the power supply 33 for
backup are built in the connecting terminal 80. When the system drive
section 45 stops because of any trouble, the blood pump 1 is driven by the
backup pump controller 30 and the backup power supply 33 inside the
connecting terminal 80.
Though not shown, the externally exposed part of the connecting section 70
is connected so that it splits at the connecting terminal 80. Moreover,
the purge tubes 24 and 25 and backup terminals of the motor cable 71 are
also built in the connecting terminal 80, and easy access is possible even
during the maintenance of the system drive section 45.
FIG. 10 shows an example of the skin button section 90. The skin button
section 90 is a structure composed of a plurality of carbon fibers having
many pores on the surface thereof, and includes a cylindrical portion 91
and a flange portion 92. The flange portion 92 is located between the
musculus rectus abdominis D and the vagina musculi recti abdominis E, and
one end of the cylindrical portion 91 reaches the epidermis F. The skin
button section 90 firmly adheres to the tissue that is in contact
therewith, prevents the separation of the connecting section 70 due to the
movement of the body, and thereby avoids infectious diseases via the
connecting section 70.
FIG. 11 shows an example of the connecting section 70. The connecting
section 70 includes the purge tubes 24 and 25, the motor cable 71, and a
protective tube 72 for covering them. The purge tubes 24 and 25 and the
motor cable 71 are helically formed, the protective tube 72 is shaped like
a bellows, and both are expandable so as not to hinder the movement of the
body of the patient. The expansion amount of the protective tube 72 is set
smaller than that of the purge tubes 24 and 25 and the motor cable 71, and
the maximum expansion amount of the protective tube 72 limits the
expansion amount of the connecting section 70, whereby the purge tubes 24
and 25 and the motor cable 71 are prevented from breaking. Furthermore,
the protective tube 72 is made of a material that is resistant to
breakage, such as Kevlar fiber, and the surface thereof is waterproofed.
Still furthermore, a plurality of circular rings 73 made of metal, resin
or the like are embedded in the protective tube 72 in order to prevent the
purge tubes 24 and 25 and the motor cable 71 from deforming and breaking
when load directly acts on the connecting section 70.
As mentioned above, according to the present invention, since the pump
controller, the purge solution circulator, the controller, the display,
the communication interface, and the power supply are made compact and
mounted on the transport section, the life outside the hospital is
permitted.
Furthermore, a plurality of pump controller and power supply make it
possible to maintain safe blood circulation under abnormal conditions.
The addition of disinfectant in the purge solution makes it possible to
prevent blood from coagulating, to remove and sterilize miscellaneous
bacteria as well as the ultrafilter, and to thereby circulate a clean p
urge solution.
The number of revolutions of the blood pump can be controlled by the
controller in accordance with the kinetic load, blood circulation can be
always kept stable and safe, and the drive condition of the artificial
heart can be monitored through the display. Therefore, the patient can
manage himself or herself, and the patient or a third person can respond
to abnormal conditions. Moreover, since the communication interface
permits the doctor and the hospital to quickly respond to abnormal
conditions of the artificial heart, the safety of life outside the
hospital is substantially improved.
The connecting terminal attached to a belt like a stomach band permits the
patient to live everyday life without worrying about its appearance. This
also makes it possible to reduce the influence of the body movement on the
epidermis.
Furthermore, since the skin button section formed of carbon fibers is
embedded in the body near the epidermis, it firmly adheres to cells,
thereby preventing infectious diseases.
In addition, since the connecting section has both expandability and
strength, ease of use and safety can be achieved.
While the present invention has been described in its preferred embodiment
applied to an artificial heart, various modifications and changes of the
embodiment may be made in the present invention within the technical scope
thereof, and the invention may be applied to a pump-oxygenator, artificial
dialysis, and the like.
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